Streaming delivery is one of the methods for delivering video via a communication network such as the Internet. With streaming delivery, one video data file is split into a plurality of segment files (split files), and these are sequentially delivered to a terminal (client) that play backs video data. The client sequentially plays back the received split files in chronological order.
Streaming delivery is broadly classified into a delivery method that uses a specific protocol such as a real-time streaming protocol (RTSP) and a delivery method that uses a hypertext transfer protocol (HTTP).
The streaming method that uses HTTP permits, for example, delivery of video with a web server alone. Further, streaming delivery that uses HTTP permits use of a cache, which results in reducing the load of a delivery server (web server). As a result, in recent years, streaming delivery services that use HTTP have been attracting attention and increasing in number.
An HTTP live stream (HLS) and MPEG-dynamic adaptive streaming over HTTP (MPEG-DASH) are examples of standards for streaming delivery that uses HTTP.
When the streaming delivery described above is performed, the client starts a playback after completing a reception of a segment file including a frame that is the beginning of video data or the beginning of a designated scene. Thus, there are a few seconds of waiting time before the playback starts in the client after a user selects video data or a scene which he/she wants to have delivered.
When splitting video data into a plurality of segment files, the split is performed by partitioning the video data, for example, for each predetermined length of time from the beginning of the video data. For HLS and MPEG-DASH, video data is partitioned into segment files whose length of time (playback time) is, for example, about ten seconds.
For example, when the playback time for one segment file is ten seconds and the transfer time of the segment file is twice the playback rate, it takes five seconds to receive the segment file. Thus, the waiting time in the client is five seconds. While this waiting time can be reduced by shortening the length of time (playback time) of each segment file, there is an increase in the load of the delivery server because there is an increase in the number of segment files and the number of communications between the client and the delivery server is increased.
The technology that is disclosed in the following document is known.                Patent Document 1: Japanese Laid-open Patent Publication No. 2013-089977        